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Nonequilibrium transport at a dissipative quantum phase transition.
Chung-Hou Chung1, Karyn Le Hur, Matthias Vojta
1Electrophysics Department, National Chiao-Tung University, HsinChu, Taiwan.
Physical Review Letters
|June 13, 2009
Summary
We studied quantum transport near a quantum phase transition using a dissipative resonant level model. The conductance shows distinct equilibrium and nonequilibrium profiles depending on voltage and temperature.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Mesoscopic Physics
Background:
- Quantum phase transitions are critical points where quantum systems exhibit dramatic changes in properties.
- Nonequilibrium transport in nanosystems is crucial for understanding quantum devices.
- The dissipative resonant level model provides a simplified yet applicable framework for studying these phenomena.
Purpose of the Study:
- To investigate the nonequilibrium transport properties of a generic quantum system near a quantum phase transition.
- To analyze the behavior of electrical conductance under finite bias voltage and temperature.
- To compare the system's response in equilibrium versus nonequilibrium conditions.
Main Methods:
- Formulation of a rigorous mapping for the dissipative resonant level model.
- Application of a controlled frequency-dependent renormalization group approach.
- Computation of nonequilibrium current under finite bias voltage (V) and temperature (T).
Main Results:
- The conductance recovers its well-known equilibrium form as the bias voltage approaches zero (V-->0).
- A distinct nonequilibrium profile for conductance emerges at finite bias voltages.
- The study provides insights into the influence of quantum phase transitions on transport properties.
Conclusions:
- The system exhibits different conductance behaviors in equilibrium and nonequilibrium regimes.
- The dissipative resonant level model, analyzed via renormalization group, accurately describes these transport phenomena.
- Findings are relevant for the design and understanding of quantum nanosystems operating out of equilibrium.
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